He rediscovered history once, and this winter, urban explorer Bob Diamond is hoping to do it again.

In January, filming of a documentary about Diamond, the re-discoverer of the once forgotten Long Island Railroad tunnel, is expected to begin, Diamond said. The other subject of the film will be the tunnel, which was built in 1844 as a route between New York Harbor and Boston, and sealed up and abandoned in 1861. The documentary has attracted the attention of several major networks, including The National Geographic Channel, according to Jerry Kolber, the film’s producer.

Diamond’s belief is that an old steam locomotive is buried within one of the tunnel walls, on the Columbia Street site of the tunnel,and the filmmakers hope to capture its discovery. Because acetylene torches were not yet available to dismantle the locomotives, it was not uncommon for them to be buried underground, he noted.

December will mark the 30-year anniversary of when Diamond, 49, was first captivated by the tunnel, hearing swashbuckling tales of its rich past about on a radio show. “That’s what started my research,” he said. River pirates were said to store their ill-gotten good there, and German saboteurs were thought to have manufactured mustard gas there during WorldWar I. Lost pages from the diary of John Wilkes Booth are also thought to be buried there.

Diamond, the founder and president of the Brooklyn Historic Railway Association (BHRA), routinely leads tours of the tunnel, located 30 feet below Atlantic Avenue between Hicks and Court streets. The subterranean jaunts have so far drawn visitors from 26 states and eight different counties, Diamond said.

The next public tour of the tunnel will be on Sunday, September 27. Call 718-941-3160 for reservations and information. Flashlights and comfortable shoes are recommended. For more information about the BHRA, go to http://www.brooklynrail.net.